1. Field of the Invention
The invention relates to an image processing system and more particularly to a method of and system for quantitatively analyzing input image(s) of an object given as an input image and in particular ultrasonic video image(s). The quantitative analysis includes the 2-D and 3-D contour extraction of the object, the calculation of the area enclosed by the 2-D contour at a slice position in the object and the calculation of volume of the body.
2. Description of the Prior Art
Japanese unexamined patent publication Hei10-99,328 (1998) discloses a ultrasonic diagnostic system for accurately recognizing and automatically obtaining the time period of the contraction last period and expansion last period of the heart.
Japanese unexamined patent publication Hei8-299,341 (1996) discloses an ultrasonic volume calculation device. Only voxels (volume cells) having link to the reference voxel out of voxels whose binary processing results are value to be extracted are separated and extracted by executing link determination operation for the binary processing results of the respective voxels so as to be set as a target region. The volume is calculated by counting the voxels in the target region.
However, conventional contour extracting system searches a wide area for contour points without limiting the search area by using information on shapes of the contour of a target organ. This may cause wrong position to be counted as true contour points due to noise or unclearness of the echo image.
It is an object of the invention to provide a method of and a system for extracting a contour of an object given as an input image and/or calculating the area or volume enclosed by the contour with a high precision, through reduced manual operation.
According to one aspect of the invention, a method of analyzing an echo image containing a contour of an organ with reduced manual operation is provided. The method includes the steps of: obtaining the echo image; (1) setting a search region including a connecting line segment connecting each pair of adjacent ones of known points on the contour; (2) setting a search line segment that originates from a point bisecting the connecting line segment of the search region and reaches an end of the search region; (3) searching each search line segment for a contour point constituting the contour; and forming the contour by connecting the contour points on the search line segments.
In one embodiment, a user manually sets four points as the known or initial points such that two of the known points provide a width of the contour and the other two of the known points provide a height of the contour.
In another embodiment, three points are set as the known or initial points such that two of the known points provide a width of the contour and the other one of the known points is on top of the contour.
According to another aspect of the invention, a method for obtaining an approximated three-dimensional contour and /or quantitative information from at least two echo images intersecting each other is provided. The method includes the steps of: specifying two points that lie on an intersecting line made by the at least two echo images and on the contour; specifying, on each echo image, two contour point providing a maximum length in a direction perpendicular to the intersecting line; extracting a contour of the organ in each echo image; setting a plurality of equally-spaced border approximation planes perpendicular to the intersecting line; and approximating a border of the organ based on intersecting points made by each border approximation plane intersecting the intersecting line and the extracted contours.